State of the state: Environment

Out-of-state water authorities paying to "seed" clouds in Colorado

A half-century after cloud-seeding began in the West, it continues to be regarded by many as something akin to chicken-noodle soup for colds. Or, on the more sinister side, snake oil.

But water authorities in Arizona, California, and Nevada don't see it that way. The three states have been pouring more money into Colorado and other headwater states in the Colorado River Basin to seed clouds.

"We're believers down here," says Tom Ryan, resource specialist with the Metropolitan Water District of Southern California. "The lower-basin folks believe it works. We believe that the science is adequate to move forward."

While still relatively small, just $152,000 this winter, the money from lower-basin states has more than tripled since 2006. The money has been used to spew silver iodide particles into clouds over the San Juan Mountains, the Gunnison Basin and Grand Mesa. Lower-basin states have also contributed to revived seeding operations at Winter Park by Denver Water and ski-area operator Intrawest.

New Mexico this winter is also contributing $25,000 to seeding of clouds in the San Juans. Colorado's state government also contributed $175,000, and local water districts, ski areas and other organizations have contributed various amounts. Vail Resorts also continues its seeding operations at Vail, as it has since 1977, the state's longest-standing seeding operation. Cost this year is $175,000.

The lower-basin states see cloud-seeding as a viable way to increase water in the stressed Colorado River Basin. Two years ago, consulting firm Black & Veatch completed a study commissioned by the lower-basin states that evaluated ways to augment existing water supplies. Desalinization of seawater was deemed highly effective but extremely expensive. The study even evaluated the feasibility of building a pipeline from the Mississippi River to the Southwest. Cloud-seeding along with removal of thirsty tamarisk plants, an invasive species found along rivers, came in as the most effective. Cloud-seeding costs little, requires few permits, and can be deployed rapidly.

Cloud-seeders insist they can augment snowpacks 10 percent to 15 percent - provided they have clouds to seed. Seeding, they say, cannot break a drought. But seeding operations remain under a general cloud of suspicion during any season. The best evidence yet comes from scientific experiments conducted during the 1960s above Fremont Pass, near Leadville.

Wanting firmer evidence, the Wyoming Legislature appropriated funding for experiments using control groups, something that the more anecdotal evidence from practitioners lacks. Those experiments are being conducted by Boulder-based National Center for Atmospheric Research just north of the Colorado border in the Sierra Madre and Medicine Bow ranges. After three winters of tests, Dan Breed, the NCAR project scientist, reports "teasers" and "trends" but not enough cases for conclusions with strong confidence levels.

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